Preparation of relief printing sheets adapted for use in hectographic reproduction of photographs



Patented Sept. 30, 1941 PREPARATION OF RELIEF PRINTING SHEETS ADAPTED FOR USE IN HEC- TOGRAPHIC REPRODUCTION OF PHO- TOGRAPHS William J. Champion, La Grange, 111., as-

signor to Ditto, Incorporated, Chicago, 111., a corporation of West Virginia No Drawing. Application June 30, 1939, Serial No. 282,200

11 Claims.

The invention relates to the multiple reproduction of photographic images by contact transfer methods and includes the preparation of relief printing sheets for use therein.

An object of this invention is the provision of photographic reproductions in the form of a gelatin washed-out relief image on a backing, the gelatin relief image being capable of absorbing and holding water soluble basic hectograph dyes in such quantity and with such sharpness as to make possible commercially satisfactory hectograph duplication of the images.

Another object is the hectograph duplication of half tone images, photographic pictures and like images having graduated tones.

Another object is the provision of means whereby representations in color obtained by photographic methods may be reproduced by a hectograph process.

Other objects and advantages of the invention will become apparent as the following detailed description progresses.

In accordance with this invention, a photographic reproduction is produced on a backing in the form of a washed-out moderately tanned gelatin relief. The relief image (known as a matrix) is saturated with a water soluble basic hectograph dye. The dye matrix so obtained contains surplus dye which in accordance with this invention is removed in a manner selected from the following:

(a) The matrix is washed with a salt solution which is substantially a non-solvent for the basic dye; or

(b) The matrix is subjected to a solution of an alkali which fixes the dye stuff in the form,

tive. The exposed portions of the gelatin become tanned and the unexposed portions remain untanned. On washing the gelatin with hot water the exposed portions remain as a gelatin relief image. A method of this general type is described in Shepherd and Bartlett Patent No. 728,310. This method, while in general operative, is not preferred since even with careful control of the time of exposure the gelatin is apt to tan and harden not uniformly and to such extent that satisfactory absorptions of hectograph dyes cannot be obtained, particularly for a reproduction of images having graduated tones. Another method which is more satisfactory is to produce a silver image by exposure through the back of an ordinary emulsion coated film and then cause the emulsion contiguous to the silver image to harden by placing it in a bath containing a tanning developer and a substance which decreases the action of the tanning developer. A suitable tanning modifier or neutralizer for this purpose is sodium sulfite. This method gives fairly satisfactory results but is not preferred for the reproduction of images having graduated tones since the tanning developer reacts to some extent with the gelatin which is not contiguous to the silver image. A more suitable method is to produce the silver image by exposure through the back of an ordinary emulsion coated film, then developing the emulsion with a non-tanning developerand after development causing the emulsion contiguou to the silver image to harden by means of a so-called tanningbleach solution, which is a solution containing an agent such as bicromate which reacts with the metallic silver of the image to form a reduction product which renders insoluble the gelatin contiguous to the silver image, and which also contains a neutralizing agent for the bichromate such as sulfuric acid.' This latter method in general gives satisfactory results.

Where it is desired to obtain a faithful reproduction of images, particularly those having graduated tones'ranging from high lights to very dark tones, it is important that the penetration of the printing light through the negative be limited in accordance with the density of the negative. This may be done in various ways, among which may be mentioned the exposure of the sensitized emulsion on the relief film through its transparent support and the limitation of the depth to which the rays of exposure; light penetrate by having the actinic rays of the exposure light and the emulsion complementary in color as described in.John Patent No. 1,453,258.

A process which has given good results inthe reproduction of images having graduated tones and which is also suitable for reproduction of images of printed matter and other representations having strongly contrasting lines is as follows: 1 w

A negative is employed to make prints by contact or enlargement on a silver halide gelatin emulsion carried by a transparent support.- A

the emulsion.

posed emulsion to produce a silver image. 1 velopment is carried to completion using a nontanning developer such as, for example, hydroquinone or .methyl paraminophenol.

I lief image or matrix.

placing the Y fi1m;in a :tank of water at; 52 C.-

suitable emulsion coated film for this purpose is known to the tradeat the time of filing this application as Eastman wash-ofi relief film. The emulsion of this film is of a type which is sensitive only to blue and blue-violet and contains a yellow dye which limits the penetration of the 1 the unexposed portion will be subsequently washed away. In printing, a small amount of light-will pass through a high density portion of a negative (corresponding to a highlight in the original subject) and will penetrate the wash off relief emulsion only a short distance. shadow in the subject produces a thin deposit of silver in the negative through which the printing light passes and then penetrates deeply into The next step is the development of the exsulting'silver image varies in depth from the support directly in proportion to its density.

The next step is to tan the gelatin which is contiguous to the light affected sensitive content of the emulsion,-that is, to the silver. This is done by a so-called tanning-bleach solution which *contains'a tanning neutralizer. A suitable solution is as follows: I

(A) Water c. c 500 Ammonium bichromate grams 20 Sulfuric acid C. P c. c 4

Water to make one liter.

(B) Sodium chloride grams 45 Water to make one liter.

The re- .a water soluble basic dye.

in a fixing solution which will not bring about further tanning of the gelatin. Such a-fixing solution is a pure aqueous solution of sodium thiosulphate. I I

It is apparent that the procedure up to this point is similar to the procedure of the Eastman wash-off relief process described in the publication of Eastman Kodak Company entitled Color Printing with Eastman Wash-Off Relief Film, No. 7734-2439, the main differences 7 being that greater care is taken to produce a moderately tanned gelatin than is necessary or called for in the Eastman process.

The next step in the preferred process of this invention is to soak the matrix in a solution of The amount of dye taken up by the matrix is proportional to the height of the relief image. The moderately tanned gelatin relief image obtained as above will absorb substantial quantities of water soluble basic dyes used in hectograph duplication such as, for example, the water soluble basic triphenyl methane dyes and the water soluble basic xanthene dyes. Such dyes include magenta, methyl violet, malachite green, brilliant green, setacyanide, rhodamines, etc.

After the gelatin matrix has become saturated with a water soluble basic dye (which usually takes five to ten minutes), the-film is plunged into a one percent ammonium hydroxide solution. This treatment fixes the dye as a free base onto the gelatin matrix. The free dye base is insoluble in water, and thus while the dye is in the form of the free base the film may be rinsed in running water to remove excess dye without removing any substantial amount of absorbed dyes The films are placed in a bath composed of one part of A, one part of Brand 6 parts of water. Sufficient treatment is given to bleach the silver of the positive to a faint brownish image, the time being of the order of 4 minutes.

By the above treatment the silver of the image is converted to silver chloride and the gelatin is tanned and hardened'wherever there is me- J tallic' silver but is not tanned and hardened where the silver halide grains were not developed. The gelatin is moderatelyand uni-.

formly tannedby this treatment. Care is taken that the 'treatment with the tanning bleach is not carried out to such' an'extent as to com- 1 pletely tan the gelatin in; any portions. The moderately tanned gelatin isinsoluble in' warm The'next' step'is the production of the re- Thismay be done by I water and varies in thickness in accordance with the density of the image.

After excess dye is removed by washing in water or other non-solvent for the dye base, the dye base is converted back into the water soluble basic dye. When volatile alkalis such as ammonia, morpholine, or thev like areused to produce the dye base, the'conversion is accomplished by evaporating the volatile alkali. Such evaporation will take place of itself in a short period of time.

The dye containing relief'image may be used in its moist or dry condition as a hectograph master. For this purpose the matrix is pressed against a hectograph blanket, thereby transferring portions of the dye to the blanket .so

be used several times until'the dye is exhausted.

It then may be re-dyed either with the same or with adifferent hectograph dye.

. master may be used a very great number of The films are lifted completelyfrom the water By this means the soluble gelatin isregelatin obtained which varies'in thickness in accordance with the density of the image.

The next treatment after the production of the gelatin relief image by washing with 'warm wa ter is the removal of the'remaining'silver chloride from the gelatin. This step is preferred although it is not an essential step. The silver chloride is removed by soaking the relief film times. I

The above processis particularly suitable for making reproductions of images having grad- It also, of course, may be used to reproduce printed matter or otherrepresentauated tones.

tions having strongly contrasting lines.-

The process may also be used for reproducing images in color by using, for example, three color record negatives instead of a single monochrome iiegative; Each color negative is used to produce a separate relief matrix. The relief image obtained from the red-filter negative is dyed with a water soluble basic dye such as Thus each sity of the image.

Victoria blue. The print from the green filter negative is dyed with a red water soluble basic dye such as fuchsine. The print from the blue filter negative is dyed with a yellow water soluble basic dye such as auramine.

It is apparent that the process can be varied considerably without departing from the spirit and scope of this invention. There may be used other photographic chemicals producing substantially the same effects or performing substantially the same function as those mentioned above by way of illustration. I may prefer in some instances to apply a slight amount of tanning with a hypo solution, although this tanning should be insuflicient to render the gelatin unsuitable to absorb hectograph dyes. AlsoI may use other alkalis than volatile alkalis to fix the dye as a free base on to the gelatin matrix. However, with the volatile alkalis, conversion of the dye base back to the water soluble basic dye is easily accomplished by simple evaporation of the volatile alkali, Whereas when non-volatile alkalis such as sodium hydroxide are used vto convert the basic dye to its base the re-conversion must be accomplished by less practical means as for example, the treatment of the dye base with a dilute acid. Furthermore, instead of converting the basic dye stuff into its free base and then washing with water or other nonsolvent for the free base to remove excess dye, followed by re-conversion of the free base into the water soluble basic dye stuff, I may use an alternative procedure consisting simply in washing the freshly dyed matrix containing surplus dye with a non-solvent for the water-soluble basic dye stuff employed. For example, I may wash the matrix with a concentrated solution of calcium chloride.

Summing up, it may be stated that the principal advantages of this invention are mainly brought about by the following features:

(1) The gelatin which forms the relief image is prevented from becoming so completely tanned and hardened that it is incapable of absorbing substantial quantities 'of water soluble basic dye stuffs. Preferably the gelatin of the relief image is produced and then maintained in a moderately tanned condition. For this purpose the use of tanning neutralizer such as disclosed in John Patent No. 1,484,029 is helpful.

(2) Excess dye is removed from the freshly dyed matrix without removing any substantial quantity of absorbed water soluble basic dye. This may be accomplished by either the nonsolvent wash method, or by the conversion and re-conversion method described above.

(3) The penetration of the printinglight is limited in accordance with the density of the negative so that the actual thickness of the gelatin relief varies in accordance with the den- This feature is particularly important when it is desired to obtain hectograph duplication of half tone images and photographic pictures. It may be accomplished by means such as disclosed in John Patent.No. 1,453,258.

While there have been shown and described certain embodiments of the invention, it is to be understood that it is capable of many modifications. Changes. therefore, may be made without departing from the spirit and scope of the invention 'as described in the appended.

claims, in which it is'the intention to claim all novelty inherent in the invention as broadly as possible, in view of the prior art.

I claim: a

1. The method of forming relief printing sheets for use in water color duplicating process which comprises selectively exposing a light sensitized silver halide gelatin emulsion on a transparent support in accordance with an original representation, developing the exposed emulsion to produce a silver image which varies in depth from the support directly in proportion to its density, tanning the gelatin contiguous to the silver image but not to the extent that the gelatin is incapable of further tanning, washing out the unexposed untanned portions of the gelatin to form a matrix having a relief image formed of partially tanned gelatin, applying a water soluble basic dye to the relief image of said matrix, and removing excess dye stuff from said matrix by washing with a concentrated neutral salt solution.

2. The method of forming relief printing sheets for use in water color duplicating process which comprises selectively exposing a light sensitized silver halide gelatin emulsion on a transparent support in accordance with an original representation, developing the exposed emulsion to produce a silver image which varies in depth from the support directly in proportion to its density, tanning the gelatin contiguous to the silver image but not to the extent that the gelatin is incapable of further tanning, washing out .the unexposed untanned portions of the gelatin to form a matrix carrying a relief image formed of partially tanned gelatin, applying a water soluble basic dye' to the relief image of said matrix, and subjecting the dye containing relief image to a volatile alkali to fix the dye as a free base on to the gelatin matrix, and Washing the matrix with a non-solvent for the dye base to remove excess dye prior to the conversion of the dye base back to soluble dye stuff on evaporation of the volatile alkali.

3. The method of forming relief printing sheets for use in water color duplicating process which comprises selectively exposing a light sensitized silver halide gelatin emulsion on a transparent support in accordance with an original representation, developing the exposed emulsion to produce a silver image which varies in depth from the support directly in proportion toits density, tanning the gelatin contiguous to the silver image but not to the extent that the gelatin is incapable of further tanning, washing out the unexposed untanned portions of the gelatin to form a matrix carrying a relief image formed of partially tanned gelatin, applying a water soluble basic dye to the relief image of said matrix, and applying to the dye containing relief image ammonium hydroxide to fix the dye as a free base on to the gelatin matrix, and washing the matrix with water prior to complete evaporation of the ammonia to remove excess dye.

4. The method of forming relief printing sheets for use in water color duplicating processes which comprises forming a matrix carrying a washed-out relief image by selectively exposing a light sensitized silver halide gelatin layer on a transparent support in accordance with an original representation, developing the light sensitized portion with a developer which has substantially no tanning action on the unexposed portions, applying to the matrix a tanning agent and a tanning neutralizer to moder ately tan the gelatin contiguous to the light affected sensitive content,. washing out the unexposed untanned portion of the matrix to 0btain a relief image, dissolving the silver halide from the matrix without tanning the gelatin by applying a fixing agent to the matrix in the absence of a tanning agent in sufficient quantity to substantially further tan the gelatin, applyhas substantially no tanning action on the unexposed portions, applying to the matrix bichromate and sulfuric acid to moderately tan the gelatin contiguous to the light affected sensitive content, washing out the unexposed untanned portion of the matrix to obtain a relief image, dissolving the silver halide from'the matrix without tanning the gelatin by applying a fixing agent to the matrix in the absence of a tanning agent in suflicient quantity to substantially. further tan the gelatin, applying a water soluble basic dye to the incompletely tanned relief image, subjecting the dye containing image to a dilute ammonium hydroxide, and washing the image with water to remove excess dye.

6. The process of forming relief printing sheets for use in water color duplicating processes which comprises selectively exposing a light sensitized silver halide gelatin emulsion on a transparent support in accordance with an orig inal representation, developing the exposed emulsion to produce a silver image which varies in depth from the support directly in proportion to its density, tanning gelatin contiguous the silver image but not to the extent that the gelatin with a basic dye, and subjecting the dyed image to a solution of a volatile alkali to fix'thedye as a free base on the matrix and allowthe removal of excess dye with a minimum of absorbed dye. W

7. As, an intermediate product in the preparation of relief printing sheets capable of use as a hectograph master; a relief image on a backing, said relief image containing a water insoluble base of a water soluble basic dye stuff. 8. As an intermediate product in the preparation of relief printing sheets capable of use as a hectograph master; a photographic reproduction in the form of a gelatin relief, said gelatin relief containing a water insoluble base of a basic dye selected from the group consisting of triphenyl methane and xanthene dye stuffs.

9. The method of duplicating which comprises forming a matrix carrying a washed-out relief image by selectively exposing a light sensitized silver halide gelatin emulsion on a transparent support in accordance with an original representation, developing the exposed emulsion to produce a silver image which varies in depth from the support directly in proportion to its density, tanning the gelatin contiguous to the silver but not to the extent that the gelatin is incapable of further tanning, washing out the unexposed, untanned portions of the gelatin to form a matrix having a relief image formed of partially tanned gelatin, applying a water soluble basic dye to the relief image of said matrix, pressing said matrix on a hectograph blanket to transfer the dye image thereto, and making impressions from the dye image on said hectograph blanket.

10. A hectograph master comprising a backing sheet having thereon a/moderately tanned gelatin relief image of substantially uniform hardness containing a water soluble basic dye.

11. A hectograph master comprising a backing sheet having thereon a photograph reproduction of an image having graduated tones, said photograph reproduction being in the form of an incompletely tanned gelatin relief of varying thickness, the thickness corresponding to variations in tones of the image, said gelatin relief containing a substantial amount of water soluble basic dye.

WILLIAM J. CHAMPION. 

